Camera surveillance is frequently used, particularly since the advent of motion cameras that register live images of a scene. For example, surveillance cameras are often used to monitor entrances, important objects and other items of interest. Many types of cameras and photographic techniques have been developed, including conventional video cameras that record moving images on a magnetic tape, for example. Digital image recording is sometimes used.
A situation that can occur is that there is something sensitive or secret in the view of the surveillance camera. There are sometimes laws and/or other regulations as to what matter a surveillance camera can capture. For example, such laws may deem it acceptable to direct the camera toward a private doorway but not to capture any view of a public sidewalk just beyond the doorway. As another example, camera surveillance may be performed to guard matters of great importance, such as classified military premises or trade secret laboratories, against unauthorized people. However, the surveillance operation can be made more difficult if the important object or premise is not to be shown to the person tasked with watching the surveillance image (i.e., the security guard). Attempts at performing surveillance have included masking of a portion of the camera image. However, this may unintentionally obstruct also important parts of the image, and it can render the camera image unnatural and difficult to survey.